Chapter 1 Introduction to Statistical Quality Control, 7th Edition by Douglas C. Montgomery.
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Copyright (c) 2012 John Wiley & Sons, Inc.
Chapter 1 Introduction to Statistical Quality Control, 7th Edition by Douglas C. Montgomery. 2
Copyright (c) 2012 John Wiley & Sons, Inc.
This is a modern definition of quality
Chapter 1 Introduction to Statistical Quality Control, 7th Edition by Douglas C. Montgomery. 3
Copyright (c) 2012 John Wiley & Sons, Inc.
The Transmission Example
Chapter 1 Introduction to Statistical Quality Control, 7th Edition by Douglas C. Montgomery. 4
Copyright (c) 2012 John Wiley & Sons, Inc.
• Less variability means better quality
• Quality improvement results in the elimination of waste. This is
useful in service or transactional businesses.
Chapter 1 Introduction to Statistical Quality Control, 7th Edition by Douglas C. Montgomery. 5
Copyright (c) 2012 John Wiley & Sons, Inc.
• Quality engineering: applying the statistical methods to ensure that
the quality characteristics of a product are at the nominal (required)
levels.
•Nominal value: desired value for the quality characteristic
•Specification: desired measurement range for the quality
characteristic
•Upper specification limit (USL): the largest allowance
•Lower specification limit (LSL): the smallest allowance
Chapter 1 Introduction to Statistical Quality Control, 7th Edition by Douglas C. Montgomery. 6
Copyright (c) 2012 John Wiley & Sons, Inc.
Statistical Methods
• Statistical process control (SPC)
– Control charts, plus other problem-solving tools
– Useful in monitoring processes, reducing variability
through elimination of assignable causes
– On-line technique
• Designed of experiments (DOE)
– Discovering the key factors that influence process
performance
– Process optimization
– Off-line technique
• Acceptance Sampling
Chapter 1 Introduction to Statistical Quality Control, 7th Edition by Douglas C. Montgomery. 7
Copyright (c) 2012 John Wiley & Sons, Inc.
Statistical Process Control (SPC)
Control charts are used for process monitoring
and variability reduction.
An on-line quality control tool.
Chapter 1 Introduction to Statistical Quality Control, 7th Edition by Douglas C. Montgomery. 8
Copyright (c) 2012 John Wiley & Sons, Inc.
Design of Experiments
• An approach to systematically varying the controllable input factors in
the process and determine their effects on the output
• They are off-line quality tools
• Crucial for variability reduction
A factorial experiment with 3 factors
Chapter 1 Introduction to Statistical Quality Control, 7th Edition by Douglas C. Montgomery. 9
Copyright (c) 2012 John Wiley & Sons, Inc.
Acceptance Sampling
Inspection and classification of a sample of the product selected at random
from a larger batch (lot) and the ultimate decision about disposition of the
lot.
Two types:
Outgoing inspection - follows production
Incoming inspection - before use in production
Chapter 1 Introduction to Statistical Quality Control, 7th Edition by Douglas C. Montgomery. 10
Copyright (c) 2012 John Wiley & Sons, Inc.
Other Aspects of Quality Control and
Improvement
• Total Quality Management (TQM)
• Six Sigma
• Origins at Motorola in 1987, expanded impact during 1990s to
present
• Focus on process improvement with an emphasis on achieving
significant business impact
• A process is an organized sequence of activities that produces
an output that adds value to the organization
• All work is performed in (interconnected) processes
• Any process can be improved
• An organized approach to improvement is necessary
• The process focus is essential to Six Sigma
Chapter 1 Introduction to Statistical Quality Control, 7th Edition by Douglas C. Montgomery. 11
Copyright (c) 2012 John Wiley & Sons, Inc.
